There are a variety of detectors that rely upon ionization. For example, ionization is used to ionize gas molecules for detecting the presence of a particular gas or substance. Smoke detectors, for example, provide an indication of the presence of smoke to alarm individuals regarding a fire condition.
Conventional detectors have utilized ionization of a fluid, such as air, for detecting the presence of smoke or another gas or substance of interest. Ionization detectors typically include a radioactive source of alpha particles such as Americium 241 for ionizing air. The alpha particles ionize air within a detection chamber. The amount of ionization varies depending on the contents of the detection chamber. When particles of smoke or another substance of interest enter the detection chamber, the particles interact with the ions and alter the ion concentration and distribution within the chamber compared to when only air is present in that chamber. Such a change in ionization is used for providing an indication of the presence of smoke, other gas, or substance of interest. This can be detected, for example, by measuring the voltage or current at a collector electrode of the detector.
One drawback associated with known detectors is that they include a radioactive material within the ionization source. One suggestion for avoiding radioactive materials is the use of current excimer sources; however, the current excimer sources are generally large in size and expensive.
Accordingly, there exists a need for an ionization source that removes radioactive substances, such as Americum-241, and/or provides a smaller, less expensive excimer source.